As to the skate scene in Ljubljana, well, there's not much too it but sure you can find some people and some interesting things to skate given it's architecture. I'd consider the city's beauty to be in the ranks with the likes of Prague, Lviv, and Krakow but then with Ljubljana you're talking a population of around 275,000 so it offers less in the way of things like nightlife. It's got a quaint medieval town feel with a castle on the hill, a nice square, and is snaked by a little river which has ornate bridges along with weeping willows on its banks. However, just a little walk from there is Metelkova that's sort of a wacky hippy commune with a good few many dive bars. Most people who aren't into nature skip Slovenia though and even the people who are into nature tend to often skip Ljubljana.
But really, I think the people make the place and the Slovenians are a grand bunch - definitely more receptive and Western thinking than the rest of the Balkans which makes sense since they were the first of the Balkan countries to join the EU plus they've got quite a bit of influence from Austria-Hungarian with a bit of Italian (fortunately they don't act like Italian women though haha).
I'm not sure what you're looking for when you say "party" but Ljubljana isn't really a party city - I'd recommend Belgrade by far if you're looking for a cheap Balkan country to go to clubs, smoke indoors, and stay out until 8am every night/morning plus even though there's not a great skate scene there's a massive skatepark in New Belgrade. Ljubljana is a city where you can see all the sights in a day or two - most people venture out to lake bled and the nature - but there's a good student scene, the best combination of friendly/beautiful women in the Balkans, and some nice bars. For reference, I wouldn't necessarily say that Slovenian girls and Croatian girls are the easiest in the Balkans but they're the most Western thinking for what that's worth. You could go party in Hvar or Split but it's too touristy for my tastes and expensive as they've sort of turned into resort towns.
If you have a chance, go to Poland. Best combination of cheap, open minded youth, partying, nice divey bars, and beautiful women along with a fascinating history. Poland is definitely my favorite country in Europe.